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<br />1 <br /> 4.1 1993 Vegetation Sampling Analysis and Discussion <br />' <br /> 4.1.1 Cover <br /> Vegetation cover sampling for 1993 is summarized in Table 35 for the Test Plots, <br /> North and South Areas, and the Shadscale Shrubland Reference Area. Cool and <br /> relatively moist spring weather accounted for eazly and increased growth in the vicinity <br /> of the mine (Reschke, 1993). Total vegetative cover on the Test Plots showed a <br /> general increase with increasing soil depth. Interestingly, the 48" soil depth on Test <br /> Plot 1 did not show increased cover over the 24" soil depth treatment. Total cover <br />' values for these two treatment plots were equal. Test Plot 1 cover values for all soil <br /> depth treatments were significantly lower than cover values for all soil depth treatments <br />' on Test Plots 2 and 3, and the North Area. Total cover in the South Area (28.4%) was <br /> only slightly higher than the 24" and 48" Test Plot 1 treatments. <br /> A general trend in cover was noted with respect to slope and aspect of the Test Plots <br /> (Table 35, Figure 18). Total cover is consistently lower on the flat aspect of Test Plot <br /> 1 compared to either the west facing aspect of Test Plot 2 or the north-northwest facing <br /> aspect of Test Plot 3. The lowest cover value of all Test Plots occurred in the 6" <br /> treatment of Test Plot 1 (12.84'0) and the highest total cover was present in the 24" <br /> treatment of Test Plot 3 (63.6%). Test Plot 2 cover values were intermediate between <br /> Test Plots 1 and 3 when comparing individual soil depth treatments. Test Plot 2 and 3 <br /> total cover values for 12" and 24" treatment plots are also greater than those of the <br /> Reference Area, which has a predominantly west-facing aspect. These observations <br />t indicate that the predominant aspect (even on the slopes of the RDA) affects the <br /> prevailing moisture regime, providing a more mesic condition favorable to plant <br /> growth on the slopes, especially the north-northwest aspect. <br />All individual treatments in Test Plots 2 and 3 (6", 12", and 24") had total cover values <br />' statistically equal to or exceeding the total cover revegetation success standard (90% of <br />the cover value with 9040 confidence) of the Shadscale Shrubland Reference Area at <br />36.0°l0 (Figure 18). Twelve and 24 inch treatments in Test Plots 2 and 3 all exceeded <br />the Reference Area cover value. Six inch treatments in Test Plots 2 and 3 were equal <br />to or exceeded the Reference Area revegetation success cover standazd when tested <br />using a Students t test (Zar, 1974, CDMG, 1988). <br />Within Test Plot 1 cover by lifeform generally increased with increasing soil depth up <br />' to 24" (Tables 3, 5, 7, 9). The 48" treatment showed a decrease in graminoid cover, <br />accounted for in part by low Bromus japonicus/tectorum cover (6.8%) compared to <br />8.04'0, 14.4%, and 12.4% on the other treatments (6", 12", 24"). Annual forb cover <br />' varied with no apparent trend. The 48" treatment was highest with 6.440 total cover <br />and the 24" treatment lowest with 0.4% cover. Woody plant cover showed a generally <br />increasing trend with soil depth. The 48" treatment was being successfully colonized <br />' 47 <br />